Self-contained breathing apparatus of the open circuit type generally employ regulator valves for regulating the pressure of the breathable gas contained in a pressurised cylinder or the like for presentation to the user at an appropriate pressure.
One particular type of pressure regulator is described in U.S. Pat. No. 4,041,978 which describes a pressure regulator for breathing apparatus having a source, i.e. a tank, containing a gaseous mixture of breathable gases, in which the regulator comprises a diaphragm case having an interior space, a diaphragm disposed in the diaphragm case, a valve housing, a moveable valve body disposed in the valve housing for opening and closing the regulator, and a control member for moving the valve body as a function of the position of the diaphragm with respect to the diaphragm case. The valve housing is divided by the moveable valve body into two or more chambers when the regulator is closed. A first chamber is adapted to communicate with the source of breathable gases and the second chamber communicates with the interior space of the diaphragm case. This regulator has an inlet for connecting the regulator to a tank containing a compressed mixture of breathable gases and an outlet for the gaseous mixture. A valve is provided for opening and closing the passage between the inlet and the outlet. The diaphragm operates the valve via a lever arrangement against the force of a valve spring. When the pressure at the outlet of the regulator becomes less than the ambient pressure acting on the diaphragm the diaphragm moves and this movement is transmitted via the lever to the moveable valve body in such a way that the valve opens. In this way breathable gas flows from the tank to the outlet of the regulator and to a mouthpiece for use by the user. As soon as the pressure at the outlet is increased so that it is approximately the same as the ambient pressure, for example during exhalation, the valve is closed by the valve spring.
The valve described in the above mentioned patent and other earlier published patents and applications, for example U.S. Pat. No. 5,503,142, US2004/0154669, EP1447320 and EP1484242, are inherently left or right handed in the sense that the valves are constructed with a single inlet on one side of the regulator valve body for connection to an inlet hose for delivering breathable gases to the regulator. In underwater and fireman's breathing apparatus the aforementioned regulator valve is often a second stage valve in the breathing circuit with a first stage valve being provided for reducing the pressure of the breathable gases in the tank from a high pressure to a low to intermediate pressure. However, the present invention is mainly concerned with so-called second stage regulator valves which deliver breathable gases at an appropriate pressure to the user via a suitable mouthpiece.
A problem that is often encountered with the aforementioned type of breathing apparatus regulator valve is that the valves are either left or right handed in the sense that the inlet is on one side of the valve body or the other, and while a left handed valve may be suitable for use with various different types of breathing apparatus it may not be suitable for others, and vice versa with respect to right handed valves. This can be a particular problem when divers or the like are likely to use the same pressure regulator valve with different breathing apparatus as known pressure regulator valves are not inherently re-configurable. Hitherto, it has been necessary for highly skilled technicians to dismantle and reassemble breathing apparatus regulator valves to change the configuration from say a left hand configuration to a right hand configuration, or vice versa. Re-configuration of the valve is therefore almost entirely impossible in the field and in the context of diving, particularly leisure diving, a mismatch between the actual and required configuration of the valve for use with a particular type of breathing apparatus may only become apparent at a late stage in the dive preparation, and thereby prevent the diver being able to use the available breathing apparatus resulting in cancellation of the intended dive.
There is a requirement therefore for a pressure regulator valve for breathing apparatus which can be readily reconfigured for connection of a breathing gas supply hose to either side of a valve housing.